# injection meaning

[ in'dʒekʃən ] Pronunciation:   "injection" in a sentence
Noun: injection  in'jekshun
1. The forceful insertion of a substance under pressure
2. Any solution that is injected (as into the skin)
- injectant
3. The act of putting a liquid into the body by means of a syringe
- shot

Derived forms: injections

Encyclopedia: Injection

[Electronics]
1. Introducing a signal into a circuit or device.
2. Introducing charge carriers (electrons or holes) into a semiconductor.

[Medicine]
n
1
a : the act or an instance of injecting a drug or other substance into the body
b : a solution (as of a drug) intended for injection (as by catheter or hypodermic syringe) either under or through the skin or into the tissues, a vein, or a body cavity
c : an act or process of injecting vessels or tissues; also : a specimen prepared by injection
2 : the state of being injected : CONGESTION —see CIRCUMCORNEAL INJECTION

[Computer]
1. <mathematics> A function, f : A -> B, is injective or one-one, or is an injection, if and only if

` for all a,b in A, f(a) = f(b) => a = b. `
I.e. no two different inputs give the same output (contrast many-to-one). This is sometimes called an embedding. Only injective functions have left inverses f' where f'(f(x)) = x, since if f were not an injection, there would be elements of B for which the value of f' was not unique. If an injective function is also a surjection then is it a bijection.

2. <reduction> An injection function is one which takes objects of type T and returns objects of type C(T) where C is some type constructor. An example is

` f x = (x, 0). `
The opposite of an injection function is a projection function which extracts a component of a constructed object, e.g.

` fst (x,y) = x. `
We say that f injects its argument into the data type and fst projects it out.

## Examples

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1. you will need an injection every four hours.
2. the morphine was administered by injection.
3. did you have gas or an injection?
4. she instructed the trainee nurses in giving injections.